YOUR alarm goes off on your phone, and instead of turning it off or hitting snooze, you pick it up and stupidly say, “Hello?”

You are, to use the technical term, in the throes of sleep drunkenness, those first few confused minutes people sometimes experience after waking. For the first time, the phenomenon — also called confusion arousal — has been studied in a general adult population, and according to a just-published paper in Neurology, this behavior is actually pretty common.

In telephone interviews the researchers conducted with more than 19,000 healthy individuals, about 15 percent reported experiencing some sort of sleep-drunk episode in the last year, and 8 percent said this happens to them at least once a week.

Most of their stories were benign, and actually pretty funny, said Stanford University School of Medicine psychiatrist Maurice M. Ohayon, who was the paper’s lead author. One man picked up his alarm clock and mistook it for his phone, holding a two-minute conversation on it. Another participant woke in the middle of the night and couldn’t find the bathroom in her own home. Other common examples are that foggy feeling you get when you first wake up with a start on a Saturday before realizing it’s the weekend, or when you wake up in a hotel room and can’t immediately figure out where you are.

For most people, and especially if this only happens to you every once in a while, it’s nothing to worry about. But for people who experience sleep drunkenness once a week or more, it could signal an undiagnosed sleep disorder. It could also be a sign of sleep deprivation, as these episodes were more common in people who’d had several nights with less than six hours of sleep in the last week. Or it could be that you’re getting too much sleep. Previous research has shown sleep drunkenness is common in individuals who reported regularly getting more than nine hours of sleep a night.

Ohayon explains that while researchers aren’t exactly sure what causes this confused behavior, animal studies give us a clue: Sudden awakenings seem to trigger the startle reflex, which allows animals (and, likely, us) to respond quickly to potential threats. To our poor, half-asleep brains, an abrupt awakening signals an emergency — a time for action, not reason.